LED lighting offers significant maintenance savings as compared to conventional high intensity lights. When properly controlled, LED lighting has a much greater service life than conventional lamps, and LED lighting does not have the intensity degradation of conventional lamps which may lose about 30% intensity in the first three months of operation. Conventional lamps are typically replaced after approximately six months of service.
All LED lighting share the same requirements. However, these requirements are not understood by many of the suppliers in the current market. Significant creative electronic design must be employed to optimally drive an LED and achieve the maximum light output per watt over a large temperature range.
Despite the maintenance advantages, prior art LED devices have not been successful in providing high efficiency solutions which provide compelling economic motivation to replace conventional lighting. Prior art devices use resistors to limit the current, do not monitor the junction temperature of the LED, and take no attention to most details of producing high efficiency lighting. Thus, there is a need for higher efficiency LED lighting systems.
A common example of prior art lighting system may be used for billboard lighting. For a large 14 foot by 48 foot billboard, four metal halide lamp fixtures are used as shown in FIG. 1. Each lamp is typically 400-500 watts. Thus, the total energy requirement may be in excess of 1600 watts.
Another example of a prior art lighting device is the Halophane™ fixture. Its distributor reports that two 400 watt lamps may be used to light a billboard.
The Adtech™ Ecotech™ series LED lights reportedly use a total of 624 watts per billboard side.
One aspect of the current invention is the ability to provide effective billboard lighting with approximately 200 total watts per side. Thus, the current invention provides dramatically higher efficiency than prior art devices. This higher efficiency is achieved with less complex devices than prior art LED lighting products such that the current invention may be sold at prices that approach conventional lighting products. The ability to provide substantially improved energy efficiency, low cost, and long-life LED devices also facilitates the use of solar, wind, or other low energy density power for the lighting devices.